Current Organic Chemistry - Volume 21, Issue 14, 2017

Polyhedral oligomeric silsesquioxanes (POSS) are perfect three-dimensional elemental building blocks that can be used for construction of diverse inorganic/organic hybrid materials. Well-defined inorganic frameworks, tailor-made physicochemical properties and symmetric distribution of organic groups make the hybrid organo-silica compounds ideal nano-fillers for polymer composites. Understanding the phenomena directing the molecular packing morphology of neat polyhedral silsesquioxanes is very important for an effective control of hierarchal structures and physicochemical properties of POSS-based hybrid materials, especially for the adjustment of polymer-nanoparticle interfacial interactions. The segmental dynamics of POSS derivatives in hybrid nanomaterials can be strongly influenced by their structural features. The review presents an analysis of intrinsic self-assembly behaviour of polyhedral silsesquioxanes and their derivatives including capability of the formation of more complex hierarchical superstructures in solid state. The stability of the formed self-assembled structures was analyzed with special regard to thermally induced solid-solid state phase transitions. The role of hierarchical structures present in a range of POSSbased advanced materials, including amphiphilic macromolecules, nanoparticles and liquid crystals is discussed.

In the recent decades, N-heterocycles are widely used as versatile scaffolds for the development of biologically active compounds and considered as one of the privileged structures. Among the various N-heterocycles, benzodiazines, a series of bicyclic heterocycles in which benzene rings are fused with 6-membered heterocycles containing two nitrogens are especially interesting, due to their structural conciseness and usefulness as synthetic intermediates, and suitable physicochemical properties as potential drug candidates and chemical probes. For this reason, a series of synthetic methodologies for benzodiazines has been developed and generally used in organic and medicinal chemistry fields. Interestingly, synthesis of quinazoline, a kind of benzodiazine in which benzene is fused with pyrimidine, has been extensively reviewed, while cinnoline, phthalazine and quinoxaline, benzene fused with pyridazine or pyrazine, have been relatively less investigated. In this review, recent advances in the synthesis of biologically active benzodiazines, benzene ring-fused 6-membered heterocycles with two nitrogen atoms, cinnoline, phthalazine and quinoxaline, will be addressed. In each section, biological activities of various benzodiazines, recently served as novel scaffolds for drug discovery, are briefly summarized for comprehensive understanding of biological and medicinal significance in advance. Moreover, intensive investigation of the synthetic approaches to various benzodiazines such as cinnoline, phthalazine and quinoxaline is followed. It would hopefully be helpful for the readers who have interests in developing novel drug candidates and related useful chemical probes.

3-(Monosubstituted)alkylideneoxindoles as one major part of the oxindoles are involved in many essential biologically active compounds, like as self-germination and tyrosine kinase inhibitors. They have been extensively used as starting materials for the synthesis of a large number of different heterocycles. The aim of this review is to give an overview of diverse methodologies that have been developed for the construction of 3-methylene and 3-(monosubstituted)alkylideneoxindoles and their utility in organic synthesis, highlighting the variety of compounds that can be directly accessed from single reactions over these systems and emphasizing the influence of the reaction conditions in the outcome of the transformations. The reactions are classified into three main categories: one-component, two-component, and multicomponent reactions.

Background: The 3-substituted 3-hydroxyisoindolinone motif is common to a variety of compounds with potent biological activities. In recent years, they have also been increasingly used as substrates in various asymmetric transformations. Current methods for their preparation either do not tolerate wide range of functional groups, or yield 3-hydroxyisoindolinones as N-substituted products, which makes them inapplicable as substrates for the asymmetric transformations. Objective: Aim of this study was a detailed examination of the synthesis of 3-substituted 3-hydroxyisoindolinones comprising various functional groups and unsubstituted phthalimide nitrogen. Method: Grignard and organolithium reagents were employed as nucleophiles for the synthesis of 3-substituted 3-hydroxyisoindolinones under various reaction conditions. Results: Phenyl substituents with electron donating groups are easily introduced by employing a Grignard reaction, while electron-poor arenes require a lithium exchange or direct lithiation strategy. The protocols are tolerant of various functional groups on the nucleophile, and a wide range of 3-hydroxyisoindolinones were afforded in good to excellent yields. Conclusion: Simple and inexpensive method for the synthesis of 3-substituted 3-hydroxyisoindolinone has been developed. By tweaking the reaction conditions, described protocols are tolerant of a wide range of functional groups, and yield 3-substituted isoindolinone alcohols with unsubstituted phthalimide nitrogen.